Don't worry, you will deal with your fair share of coolant leaks on the 4.2 ...

 

Haven’t had one yet after 13 years.

EDIT: for clarification, the X150 XKR hasn’t had a leak in 13 years. I’ve had 6 Jags and none had leaks in 20+ years even having done over 100K miles. Also no plastic to be found in the cooling circuit, either metal pipes or standard hoses.

Then someone said let’s build it better and replace metal and reinforced rubber with glued together plastic bits….

 

and the 4.2 in the X150 is the final evolution of the AJ 4/4.2L that started in the X100 XK8. The 4L motors have timing chain tensioner and to a lesser extent guides problem, early cars have crap water pumps, the cylinder linings were nikasil before we had the fuel to not destroy them, etc.

The 5L as it premiered in the X150 similarly had teething problems just like the previous engine did early in their lifespan. I bet money that later F types with the 5L will be less problematic on the same reasoning.

The 5L is a relative monster of Performance and considering the issues they have in early form, it’s not that bad considering; especially when compared to German competition like the 6 series and the CL/SL.

 

Sorry, I was only referring to the 4.2 fitted to the X150, suppose I could've been more specific. I've had 6 variations of the 4, 4.2 & 4.4 litre and had NO issues with any of them, even after 100K miles, other than a Denso TB on the 2005 Super V8.

I've had 3 of the new engines in 5 litre supercharged and 3 litre supercharged, even recent models and ALL have had the exact same issues that EVERYONE else has, so no JLR never got them right, even after years.

 

nah I kind of glossed over it but I was trying to imply the X150 4.2 benefited from the work done earlier in the engine series’ life when it was more problematic; just like early 5L cars are paralleled in that they got better later.

Turns out I’m wrong on the 5L getting better but I’m happy with my little 4.2L XKR and not still quite sure I like the F type, so I might never know from my own experience on the 5L cars. I’m likely to replace my 07 XKR with a 4.2L XKR Portfolio as the mileage gets up there as I’ve had a very positive ownership experience and want to repeat it with Alcon brakes and fancier speakers lol.

 

No, you're right about the 4X litre AJ26 through AJ34S, they kept getting better and better over time, performance and reliability. Sadly not the case with the completely different AJ133 5 litre and 3 litre derivative, though they did address the chain tensioner issue fairly early on, it wasn't until recently the front crossover pipe was redesigned (2017 or 2018, I think), but pulleys, belt tensioners, water pumps, other coolant pipes, injectors, valves have yet to be addressed. Yes it can make gobs of power, but I'll stick with the last gen AJ34S for reliability, especially for road course racing.

 

hmmmm.... so given that I just bought an xf Sportbrake with 35k miles, what can I look forward to?

 

No doubt… just a matter of when.
But at least they won’t be from this manifold monstrosity.

 

coolant leaks from all the same locations.

the 5.0 and the mickey mouse 3.0 V6 are not very good engines. one minor overheat = engine done = totaled car

 

two rubber hoses in the valley that go to the thermostat crossover

sometimes they leak a little

 

well I did have an overheat at about the 85,0000 mile mark on my XKR. Scorching day in LA and the relay that turns on the cooling fan had fried out. I was stopped on the highway and it was actually on for about ten minutes, fortunately when traffic eased and i headed downhill it went off. issue was fixed and it’s been fine since then, including two cross-country drives. Never gave it a second thought.

 

I had all of the plastic coolant hoses and pieces, including the valley hose and thermostat, replaced on my 2014 XKR last year with only 18,000 miles by the dealer when I had the car in for the SC torsion isolotor replacement under certified warranty. I paid for the extra parts and incremental labor cost. It was a great opportunity to update the parts for preventative maintenance. The newer plastic parts are one piece and are not welded together.

 

As I said before, the front crossover WAS redesigned as a single piece as it should have been. Like you I had ALL pipes and hoses replaced last year at the main dealer. However for the rear crossover, the JLR tech showed me side by side there’s no difference in the factory fitted leaking one from 2015 and 2020 JLR supplied replacement. The tech and I had this very same conversation and he agreed how odd it was the front wasn’t redesigned until 2017/2018 and the rear hadn’t been redesigned at all despite every single one failing at the seams.

 

ive had 2 -4.2 and 2 -5.0 SC engines with no issues after 100k miles other than regular maintenance. I did have water pump leaks but what car doesn’t.
both the 4.2 and the 5.0 are great engines.
but dont get me started on the 3.0 sc its a engineering fail on epic proportions…[ ive gone through 2 of them both at 70k miles]. Not to say there are no issues with plastic pipes on the 4.2/5.0 ( more so when they are welded horizontally ) they all eventually fail… that said its not necessarily going to happen pre maturely… i always replace plastic parts (every 6-8 years) particularly ones that go through a lot of heat cycles …its the cost of performance for every manufacturer.
With monster power comes more maintenance its a given. I realize most forums post issues over praise…thats why they exist (to help with issues) but don't let that be discouraging there are many positive experiences and I’ve had many.
my2c

 

All I can say is.... ouch.
they took off 10% so it was closer to $2,000, but still.... ouch. (And you gotta love a hundred bucks worth of anti freeze)


Again... ouch.

 

genuine jaguar antifreeze

the oldest trick in the book

 

Right, so, for clarification, the 4.2 supercharged does NOT have plastic coolant pipes. The NA version of the 4.2 doesn't have plastic pipes either, although unlike the XKR, it does have a plastic thermostat housing which are known to crack and leak.

Coolant leaks are NOT unique to JLR, though some makes/models are less prone to leaks.

There's no glaring engineering issues between the 3 and 5 litres, they're both the same engine with the same parts.

Perhaps it's my opinion but I don't think any of these cars would be quoted as having monster power and regardless, 300 to 400 to 500 horsepower would have absolutely NOTHING to do with increased parts failure, in fact these engines are deliberately de-tuned to reduce wear and tear.

Spoke with someone at JLR today and they posed the reason the front crossover was re-engineered and the rear was not was due to complexity of design of the rear manifold crossover, and that does make sense and thye typically last as long as the warranty does which in the end is all that matters to the manufacturer.

 

They are very different where it counts. the crank is obviously different (read weak) although the same length….it has two dead cylinders to cover which is a design flaw imo. It likes to spin bearings on #2 cylinder happened to me on 2 different 3.0’s that were meticulously maintained.
Not sure why that engine ever existed.. not only is it lethargic but it burned the same amount of fuel as my 5.0’s…plus there’s a very big difference in sound That equals zero benefits in my books.

fyi) monster power on the 5.0 is there not sure what you think monster power is…but its not just a number. Drive a SVR F Type or a Project 8

 

The few V6 engines I’ve had from various marques have always had worse fuel consumption than any V8 so I reckon that’s not a JLR issue. And I agree it’s not enough power especially for 7000 pound Land Rovers. But it’s not nearly as bad as the massively underwhelming 4 cylinder, and they put those in Range Rovers 🤦🏻‍♂️, talk about slow, I can walk faster.

But I’ve not experienced the issues you’ve described, even having done over 100k miles.

In my opinion monster power is well over 700 HP, not 300, not 400 and not 500 found in JLR vehicles. The ultra limited production project 8 and SVRs really don’t count but I reckon if you compare a 300 HP V8 XK to an FType SVR with nearly twice the power it’s seems like a lot. But your statement indicated the failures on these cars was due to them having monster power and that failures should be considered normal because of that.